GPT-5.1-Codex

openai/gpt-5.1-codex

A chat model with a 400K-token context window, at $1.3125 per million input tokens and $10.50 per million output tokens.

Details

Maker: openai
Kind: Chat
Context window: 400,000 tokens
Max output: 128,000 tokens
Input: $1.3125 per million tokens
Cached input: $0.1365 per million tokens, 90% off
Cache write: Same as input
Output: $10.50 per million tokens
Capabilities: Reasoning, tool use, vision, file input, web search
Takes: Text, image, pdf
Returns: Text
Zero data retention: Yes, on every provider
No training on requests: Yes, on every provider
Released: 2025-11-12
Newer model: openai/gpt-6.1-sol-batchReleased later by the same maker, costs no more, and lists the same capabilities. Compare the two

Description

GPT-5.1-Codex is a version of GPT-5.1 optimized for agentic coding tasks in Codex or similar environments.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex",
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Set PHANTOM_KEY to your key. Any OpenAI client works with the base URL https://phantom.codes/v1.

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